Wireless communication is well known in the art. Heretofore, one type of wireless communication is known as a "cellular" communication wherein each stationary unit receives and transmits signals to mobile units within its allocated geographical region, called a cell. As mobile units move from one cell to another, communication is transferred from one stationary unit in one cell to another stationary unit in another cell.
Heretofore, cellular communication is analog based and has risen in popularity. However, as a result, the airways have become increasingly crowded and the capacity of the communication system to take on new subscribers is becoming increasingly of a problem. Digital cellular communication offers an opportunity to increase the number of subscribers to operate within the cellular system. However, to bridge the gap between the current analog cellular system and the digital cellular system, a standard has been proposed. The standard proposed by EIA/TIA (Electronic Industry Association/Telecommunications Industry Association), known as the IS-54 standard, specifies that communication between a mobile unit and a base unit should be capable of operating in both the analog and the digital mode. More particularly, when operating in the digital wireless communication mode, the IS-54 standard specifies that communication between a base unit and a mobile unit occur in a Time Division Multiplex Access (TDMA) la mode. In a TDMA mode, the digitally encoded signal is transmitted in a plurality of non-contiguous time slots. Communication between a base unit and a mobile unit occurs in an assigned time slot, within each frame. In each time slot, digitally encoded synchronization signal must first be transmitted followed by the digitally encoded data signal. Furthermore, within the digitally encoded data signal, at a predetermined time period, a digitally encoded marker signal is transmitted. These are all well known standards in the IS-54 specification.
One of the problems of a digital wireless communication system is the problem of equalizing the digitally encoded signals. As the digitally encoded signal is transmitted from one unit to another, through a multiplicity of data paths, the various signals arriving at the other unit can cause delay spread between the digitally encoded signals. This is known as inter-symbol interference. An equalizer is a digital hardware/software apparatus which corrects inter-symbol interference between the digitally encoded signals arriving from a plurality of signal paths.
In the prior art, a number of equalization strategies is disclosed. See, for example, "BER Performances Of Mobile Radio Equalizer Using RLS Algorithm In Selective Fading Environment" by Akihiro Higashi, Hiroshi Suzuki; "Bi-Directional Equalization Technique For TDMA Communication Systems Over Land Mobile Radio Channels" by Yow-Jong, Liu, page 1458-1462, Globecom '91; and "Development Of Japanese Adaptive Equalization Technology Toward High Bit Rate Data Transmission In Land Mobile Communications" by Seiichi Sampei, page 1512-1521 IEICE Transactions, Volume E, 74, No. 6, June, 1991.
Although the present invention, in the preferred embodiment, discloses a wireless communication systems using the IS-54 standard capable of operating in both analog and digital mode, it should be apparent that the invention, as set forth herein, can be used in any digital, wireless, communication system.